In general, various structures in machinery, construction, and civil engineering fields and parts for electronic apparatuses as well as transporters such as an aircraft, a motor vehicle, and a train are often exposed to extreme environments such as changes in temperature and scratches as well as various types of loads and impacts involving changes in pressure as they are, and in this case, these are required to be designed to withstand the extreme environments.
For example, a motor vehicle (10) which undergoes high-speed running throughout the year to be exposed to extreme environments such as significant changes in temperature, changes in pressure, strong wind loads, impacts, and scratches is illustrated in FIG. 1. In the case of the motor vehicle (10), the panel used in the car body is required to be fabricated to be light and to exhibit high-level mechanical strength properties so as not to be easily damaged in response to the extreme environments.
Accordingly, a pressed steel plate is typically used as the material of the panel applied to the body of the motor vehicle (10) so as to meet the mechanical strength properties in response to the extreme environments, but the weight of the pressed steel plate is significantly heavy to be the main factor of the retrograde movement to the weight reduction being an issue in recent years. Hence, in recent years, a high strength steel for motor vehicle, magnesium, and aluminum are adopted and used as a light weight material for some panels for the motor vehicle (10). These materials are spotlighted as a light weight material despite a high stiffness. Among these, the high strength steel has advantages to increase economic efficiency by reducing the total vehicle weight and to enhance the high-speed stability and quietness by maintaining a robust car body. More recently, a carbon fiber reinforced plastic (CFRP) which has been mainly used in fuselage parts for aircraft has attracted attention as a future core material for weight reduction. CFRP is produced by subjecting an acrylic fiber to a special heat treatment, and its weight is only half of iron and about 70% of aluminum. However, CFRP has an advantage that its strength is as high as about 10 times iron.
However, although such new materials have attracted attention, there are significant constraints in general use of such new materials in the market due to price competitiveness and rarity of the materials. Hence, in recent years, the development of a new composite material or structure that can replace the existing panel for car body is accelerated, and such a technology development is actively discussed not only in the motor vehicle field but also in the transporter field such as aircraft and train. The machinery, building, civil engineering fields.
Especially, an attempt to apply an excellent structure that is present in a natural living body such as abalone shell and exhibits high mechanical strength properties while having a light weight is recently made in order to develop new functional materials. In the case of such an excellent functional structure present in the natural living body, an attempt to carefully analyze the excellent functional structure has been made by a number of pioneering researchers, but satisfactory results are not obtained and such an attempt is at a standstill since there are technical difficulties in the structure analysis and simplifying operation by which the structures found in nature are generalized and generally used, and in the manufacture of the actual product.